Tag Archives: oceans

Dying Coral Reefs

by Krista Bergesen

With the global climate changes going on right now, it may not be surprising to know that the aquatic life is also being affected. Displayed in every vacation resorts catalog and ocean documentary, coral reefs have formed an integral part of the planet’s oceans, providing a food supply, habitat, and protection for many other sea creatures.

Sometimes, it is easy to imagine coral as the dead, funny shaped rock that can be seen when you go scuba diving. Surprising as it may be, coral are actually living animals that eat, breathe, and reproduce.

Often mistaken for plants, coral use tentacles to sting and capture their prey of small fish and small animals. Hard to imagine, right?

It may be interesting to note that coral also located all across global waters. In colder northern waters, the coral don’t generally settle down into the picturesque colonies of the equatorial waters, but are still there floating aimlessly throughout the water. Large colonies are formed in the presence of algae, where the coral can feed off of the algae’s products of photosynthesis. At the same time, the coral produce CO2 to feed the algae. Not having to capture prey anymore because of this mutualistic relationship, the coral then produce the calcium carbonate exoskeletons that people usually identify with the species.

Coral reefs may look rock hard and impermeable, but they are surprisingly fragile.

Myriads of creatures graze on and make their homes in the coral. And the coral are always dying and re-growing their structures because of the constant attack they are under. A very delicate balance of destruction and growth has been maintained for millions of years between the coral and the rest of the ocean. It figures that humans would mess it up.

Instead of carrying fresh, clean water to the oceans, rivers now carry agricultural waste. Nitrates, phosphates, sewage, etc. now pollute the water. Recent evidence has found that coral now faces disease susceptibility from the sediment accumulation and increased exposure to land-based pathogens.

It doesn’t stop there, global warming has, not surprisingly, caused problems as well. As coral and algae colonies evolved together in a very narrow temperature range, the algae have begun to produce poisonous oxygen compounds called “superoxides” because of the higher oceanic temperatures. The coral will consequently expel the algae only to starve and turn a deathly white, giving the process the name of “bleaching.”

Coral reefs only form a small portion of the vast oceans, but their presence showcases the biodiversity and intricacy of the ocean’s natural systems. Widespread coral bleaching as well as pollution will change the face of the oceans as we know it through extinction. And this type of change cannot be undone.


Leave a comment

Filed under Biology, Ecology

Ghost Fishing

By: Kimmie Riskas

Before the widespread use of synthetics in the 1950s, all fishing gear was made from natural fibers, typically hemp and cotton, and strengthened with a coating of tar or strips of canvas. If lost or discarded at sea, the natural fibers would quickly lose buoyancy, disintegrate, and be chewed into nothingness by marine microbes.

Plastics, however, are durable, lightweight, and cheap, which is why synthetics have almost entirely replaced natural fibers in fishing gear over the last 35 years. Synthetic gear doesn’t break down as readily under prolonged submersion and UV light bombardment as hemp does. Decomposition by algae and colonial invertebrates happens more slowly on synthetic gear, if at all. It’s cheaply mass-produced. If broken or mislaid, synthetic gear is readily dumped overboard, left to drift through the oceans intact. There’s evidence that plastics may last even longer in the ocean, where salinity, temperature, and varying periods of exposure to direct sunlight prolong the plastics’ life far past that of plastic abandoned on terra firma.

All these long-lasting ropes, nets, and lines in the ocean carry unintended consequences for the creatures unfortunate enough to come across them. It’s called ghost fishing, and it’s responsible for the deaths of thousands of seabirds, whales and dolphins, sea turtles, marine mammals, fish and crustaceans every year. Discarded nets and lines quickly accumulate growths of marine algae and fouling colonies of invertebrates (barnacles, crabs, anemones, worms, and the like). Fish predators attracted by this floating buffet meet their death by entanglement. The gear accrues such masses of algae, debris, and dead animals that it sinks under the weight, hovering under the surface at anywhere from twenty to two hundred meters. Once some of this organic load rots away, the ghost nets rise vertically in the water column via buoyant plastic floats, to ensnare more wildlife and being the cycle over again.

A 1997 study by D.W. Laist in the Marine Pollution Bulletin by found that marine debris harms more than 267 species worldwide, including 86% of all sea turtle species, 44% of all seabird species, and 43% of all marine mammal species. In 2000, a single, derelict net recovered in Alaskan waters contained 350 dead seabirds and hundreds of rotting salmon. Sea turtles often mistake floating plastic bags for the diaphanous jellyfish that make up the bulk of turtles’ diets; hundreds of whales and dolphins wash ashore annually whose stomachs and respiratory tracts are choked with plastic sheeting and packaging material. Ghost nets are also destroying coral reef communities, snagging and breaking the very structure of the reef as the nets are dragged along by currents.

In 1975, having completed the transition to synthetic fishing equipment, international fisheries collectively dumped 135,400 tons of plastic gear into the world’s oceans. Although it’s difficult to measure exactly how much of it is floating in the ocean today, expansion of international fisheries and shipping industries since 1975 suggests that the amount of jettisoned fishing paraphernalia has significantly increased as well. The dumping of plastic trash and fishing gear from ships at sea has been banned since 1990 by international shipping regulation MARPOL Annex V. While there is some indication that the amount of discarded flotsam and jetsam has declined slightly in well monitored areas since the ban’s implementation, the vast majority of the world’s oceans are unpatrolled and regulations remain unenforced. An estimated 6.5 million tons of plastic debris are still dumped overboard every year.

Despite the damage caused by ghost fishing in the world’s oceans, discarded fishing gear accounts for a small percentage of marine debris. Litter composition varies by area, reflecting local use of containers, packaging, and fishing equipment. For example, in the eastern China Sea, where fishing is the dominant economic activity, 72% of marine debris originates as nets, ropes, and buoys discarded from fishing vessels. In Jakarta Bay, Indonesia, 42% of marine debris is polythene plastic bags; fishing here has been curtailed as increasing discharge of sewage and industrial effluent from the nearby city poison the water and make commercial fishing unprofitable.

Leave a comment

Filed under Biology, Ecology, Policy